DOCSLIB.ORG

Thz Low Resolution Spectroscopy for Astronomy Gordon J

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Thz Low Resolution Spectroscopy for Astronomy Gordon J IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY, VOL. 1, NO. 1, SEPTEMBER 2011 241 THz Low Resolution Spectroscopy for Astronomy Gordon J. Stacey (Invited Paper) Abstract—The THz spectral regime provides a wide range of new astrophysical discoveries, Section IV is a discussion of the spectral lines that are invaluable probes of star formation and merits of direct detection systems, Section V gives examples of AGN activity in galaxies both in the local Universe and at the moderate resolving power direct detection systems that are used earliest times. We review the utility of these lines, give examples of the science they deliver, and detail the properties of successful for astrophysical experiments today, and Section VI discusses low resolution direct detection spectrometers for work in the THz some of the prospects for future work. regime. We finish with a discussion of the exciting new science we expect with the next direct detection generation spectrometers on II. ASTROPHYSICAL PROBES WITHIN THE THZ BANDS new facilities such as SOFIA, CCAT, SPICA, and ALMA. A. Fine-Structure Lines Index Terms—Direct detection receivers, extragalactic spec- troscopy, fine-structure lines, TH spectroscopy. Atoms or ions with ground state electronic configurations that contain valence electrons will have their configurations ordered by the residual electrostatic interaction into terms that differ in I. INTRODUCTION the total (vector) orbital angular momentum and HE THz spectrum, here loosely defined as frequencies total (vector) spin angular momentum .Theseterms T between 600 GHz and 6 THz, contains a plethora of are donated by , where the superscript is equivalent readily detectable spectral lines that are important diagnostics to the number of levels into which the term is split, and P de- for both the physical and chemical conditions of the gas and notes the total orbital angular momentum of the electronic term the sources of energy within astrophysical environments. These and follows the usual convention where refer to spectral probes include rotational lines from simple molecules terms of . These terms are further split by the (e.g., HD, CH, OH, CO, , ), and the ground state spin-orbit interaction into levels where the subscript J fine-structure lines from abundant atoms and ions (e.g., C, denotes the magnitude of the vector sum of and . , , ,O,and ). These lines are well explored in Each of these levels, J, has a degeneracy given by . both galactic and extragalactic environments, and indeed the When an atom or ion has 1, 2, 4, or 5 equivalent p electrons in molecular lines can be important probes of planetary atmo- its ground state configuration, the ordering and selection rules spheres in the solar system. Important results are obtained with dictate that its ground state term will be or terms, so that both coherent (heterodyne) and incoherent (direct detection) it has ground state fine-structure lines. After H and He, which spectrometers. Here we focus on work done with direct detec- have no significant lines in the THz regime, the three most abun- tion spectrometers whose natural niche is the broad spectral dant elements in the Universe are oxygen, carbon, and nitrogen line environment of extragalactic studies. In this context, line with relative abundances ,3,and with respect to widths are to 500 km/sec, the smaller values typical for hydrogen respectively. Amongst these elements, the O, , low mass dwarf galaxies and spiral galaxies viewed “face-on” C, , ,and ionization states have ground term split and the larger values more typical for more massive systems into fine-structure levels that emit photons in the THz range with more arbitrary presentations on the sky. This narrows our (Table I). Since transitions within a term involve no change focus to the lines with large luminosities on galactic scales. in the electronic configuration, they are forbidden to electronic These are the lines that are important coolants of the interstellar dipole radiation and decay by magnetic dipole transitions. As medium (ISM) including the fine-structure lines of C, , , such, the excited fine-structure levels are metastable with life- ,O,and , and the mid-J rotational lines of CO. times measured in days. This paper is divided into five sections. Following this intro- Since they lie in the THz range, where the corresponding duction, Section II discusses these spectral lines and their utility wavelengths 100 m are large compared to the typical sizes as probes of astrophysical environments, Section III is a brief of interstellar dust grains 0.1 m , these lines are largely history of observations of these lines including some exciting unaffected by the interstellar extinction by grains that hinders optical and near infrared observations. With weak Einstein A coefficients, the lines are also not usually affected by self-ab- Manuscript received April 08, 2011; revised June 06, 2011; accepted June 07, sorption (they are optically thin) so that typical photons will es- 2011. Date of current version August 31, 2011. This work was supported in part by NSF Grants AST-0705256 and AST-0722220. cape an emitting gas cloud. Furthermore, the energy levels that The author is with the Department of Astronomy, Cornell University, Ithaca, emit the lines lie within a few hundred K of the ground state, so NY 14850 USA (e-mail: [email protected]). that they are easily collisionally excited by electrons, H, or Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. impacts in many astrophysical environments. The combination Digital Object Identifier 10.1109/TTHZ.2011.2159649 makes these THz lines important coolants for many phases of 2156-342X/$26.00 © 2011 IEEE 242 IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY, VOL. 1, NO. 1, SEPTEMBER 2011 TABLE I above ground state) are much less than the ionized gas temper- SELECTED THZ SPECTRAL LINES. atures , so that level excitation is very insensitive to gas temperature. However, neutral oxygen and carbon are found in neutral gas regions where gas temperatures are typi- cally between 50 and 1000 K. Therefore, their line ratios are sensitive to gas temperature. The critical density of the neutral carbon lines are relatively modest so that the levels are typically thermalized at the densities found in interstellar gas clouds. As such, the [CI] line ratio has proven to be a good temperature probe, and the lines trace gas column density, hence mass. The THz frequency fine-structure lines are also excellent probes of the hardness of the ambient interstellar radiation fields. The vast majority 90 of stars in galaxies like the Milky Way are on the main sequence (MS) where they are fusing hydrogen into helium in their cores. Within the main sequence, stellar luminosities, are strongly dependent on stellar mass, . Due to the steep dependence of L on M, the most massive stars are not only the most lu- minous MS stars, they also have the shortest MS lifetimes, . Furthermore, the most massive MS stars have the highest surface temperatures, , so that they dominate the interstellar UV radiation fields. Therefore, presuming a stellar photospheric origin, a harder ambient UV radiation field indicates more massive stars on the main sequence, hence a younger stellar population. The fine-structure lines trace the the ISM and excellent probes of the physical conditions of the radiation field hardness, hence the age of the stars. It takes 14.5 gas clouds and tracers of the sources of heat, be it the radiation eV photons to form (equivalent 33 ,oraB0 fields from nearby stars or AGN, cosmic rays, X-rays or inter- star), and 29.6 eV photons to form ( 39 or stellar shocks. an O8 star). Therefore, the [NII]/[NIII] line ratios are strongly indicative of the hardness of the ambient interstellar radiation B. Ionized Gas Lines field (Fig. 2). With an ionization potential of 35 eV, takes even harder UV photons to form than . Therefore, the Ionizing hydrogen requires photons with energy greater [OIII]/[NII] line ratios are even stronger indicators of .The than 13.6 eV, so species that require more than 13.6 eV pho- [OIII] 88/[NII] m line is especially useful since the levels 1 tons to form will be found exclusively within HII regions that emit these lines have similar critical densities (Table I), so , and those with ionization potentials less that the resulting line ratio is very insensitive to density as well than 13.6 eV (O, C) will be found exclusively in neutral (hy- (Fig. 3). drogen) gas clouds. takes only 11.3 eV photons to form, but 24.4 eV to further ionize so that it is found both in neutral and C. Neutral Gas Lines ionized gas clouds. Fine-structure lines are excellent probes of gas density. Fig. 1 shows this sensitivity for the [NII] line pair.2 In astrophysical environments, as one moves away from the Within a species, two fine-structure lines will have different source of ionizing photons there is a transition from regions Acoefficients, hence different critical densities for where hydrogen is fully ionized (the HII region) to the neutral thermalization of the emitting levels. In the low density limit gas clouds beyond. While HII regions and neutral gas clouds , every collisional excitation leads to the emission have size-scales of the order 10 parsecs cm ,the of a photon, so that the line ratio is constant. In the high density transition between the two is fairly abrupt. It is roughly given by limit , the levels populations are thermalized, and the mean free path of a photon that is capable of ionizing H, or given by the Boltzman formula therefore yielding a second 0.01 pc for typical interstellar gas densities. Photons with en- constant line ratio.
Load more

Recommended publications
  • Review of the State of Infrared Detectors for Astronomy in Retrospect of the June 2002 Workshop on Scientific Detectors for Astronomy
    Review of the state of infrared detectors for astronomy in retrospect of the June 2002 Workshop on Scientific Detectors for Astronomy. Gert Fingera and James W. Beleticb a European Southern Obseravatory, D-85748 Garching, Germany b W. M. Keck Observatory 65-1120 Mamalahoa Hwy., Kamuela, Hi 96743, USA ABSTRACT Only two months ago, in June 2002, a workshop on scientific detectors for astronomy was held in Waimea, where for the first time both experts on optical CCD’s and infrared detectors working at the cutting edge of focal plane technology gathered. An overview of new developments in optical detectors such as CCD’s and CMOS devices will be given elsewhere in these proceedings [1]. This paper will focus on infrared detector developments carried out at the European Southern Observatory ESO and will also include selected highlights of infrared focal plane technology as presented at the Waimea workshop. Three main detector developments for ground based astronomers are currently pushing infrared focal plane technology. In the near infrared from 1 to 5 mm two technologies, both aiming for buttable 2Kx2K mosaics, will be reviewed, namely InSb and HgCdTe grown by LPE or MBE on Al2O3, Si or CdZnTe substrates. Blocked impurity band Si:As arrays cover the mid infrared spectral range from 8 to 28 mm. Since the video signal of infrared arrays, contrary to CCD’s, is DC coupled, long exposures with IR arrays are extremely susceptible to drifts and low frequency noise pick- up down to the mHz regime. New techniques to reduce thermal drifts and suppress low frequency noise with on-chip reference pixels will be discussed.
    [Show full text]
  • Absolute Radiant Power Measurement for the Au M Lines of Laser-Plasma Using a Calibrated Broadband Soft X-Ray Spectrometer with Flat-Spectral Response Ph
    Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response Ph. Troussel, B. Villette, B. Emprin, G. Oudot, V. Tassin, F. Bridou, Franck Delmotte, M. Krumrey To cite this version: Ph. Troussel, B. Villette, B. Emprin, G. Oudot, V. Tassin, et al.. Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat- spectral response. Review of Scientific Instruments, American Institute of Physics, 2014, 85 (1), pp.013503. 10.1063/1.4846915. hal-01157538 HAL Id: hal-01157538 https://hal.archives-ouvertes.fr/hal-01157538 Submitted on 16 Nov 2015 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. REVIEW OF SCIENTIFIC INSTRUMENTS 85, 013503 (2014) Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response Ph. Troussel,1 B. Villette,1 B. Emprin,1,2 G. Oudot,1 V. Tassin,1 F. Bridou,2 F. Delmotte,2 and M. Krumrey3 1CEA/DAM/DIF, Bruyères le Châtel, 91297 Arpajon, France 2Laboratoire Charles Fabry, Institut d’Optique, CNRS, University Paris-Sud, 2, Avenue Augustin Fresnel, RD128, 91127 Palaiseau Cedex, France 3Physikalisch-Technische Bundesanstalt (PTB), Abbestr.
    [Show full text]
  • Template BR Rec 2005.Dot
    Report ITU-R M.2442-0 (11/2018) Current and future usage of railway radiocommunication systems between train and trackside M Series Mobile, radiodetermination, amateur and related satellite services ii Rep. ITU-R M.2442-0 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio- frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http://www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Reports (Also available online at http://www.itu.int/publ/R-REP/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management Note: This ITU-R Report was approved in English by the Study Group under the procedure detailed in Resolution ITU-R 1.
    [Show full text]
  • Vector Quantization for Spatiotemporal Sub-Band Coding by Pasquale Romano Jr
    Vector Quantization for Spatiotemporal Sub-band Coding by Pasquale Romano Jr. A.B., Computer Science Harvard University Cambridge, Massachusetts 1987 SUBMITTED TO THE MEDIA ARTS AND SCIENCES SECTION IN PARTIAL FULFILLMENT OF THE REQUIREMENTS OF THE DEGREE OF MASTER OF SCIENCE AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY February 1990 @Massachusetts Institute of Technology 1989 All Rights Reserved Signature of the Author . ..... ... .. f Pasquale Romano Jr. Media Arts and Sciences Section September 28, 1989 In Certified by ............ ............. '............... / .... d w....... .p. .. a... Andrew B. Lippan.1u/ Lecturer, Associate Director, Media Laboratory Thesis Supervisor . I P_ Accepted by Stephen A. Benton Chairman Departmental Committee on Graduate Students mAssACHUSETTS INS OF TEcwQLOGY FEIB 27 1990 Rotert Vector Quantization for Spatiotemporal Sub-band Coding by Pasquale Romano Jr. Submitted to the Media Arts and Sciences Section on September 28, 1989 in partial fulfillment of the requirements of the degree of Master of Science at the Massachusetts Institute of Technology Abstract This thesis investigates image coding using a combination of sub-band analysis/synthesis techniques and vector quantization. The design of a vector quantizer for image sub-bands is investigated, and the interplay between multi-rate filter banks and the vector coder is examined. The goal is twofold, first, a vector quantizer that is bounded by a distortion criterion versus an apriori fixed limit is essential to more optimally allocate bits in a sub- band coding system. This is due to the dynamic nature of the energy distribution in the sub-bands. Second, parameters for the vector quantizer that are psychophysically and statistically well matched to the characteristics of image sub-bands must be determined.
    [Show full text]
  • Federal Communications Commission
    Vol. 80 Thursday, No. 127 July 2, 2015 Part IV Federal Communications Commission 47 CFR Parts 2, 15, 80, 90, et al. WRC–12 Radiocommunication Conference (Geneva 2012); Proposed Rule VerDate Sep<11>2014 21:32 Jul 01, 2015 Jkt 235001 PO 00000 Frm 00001 Fmt 4717 Sfmt 4717 E:\FR\FM\02JYP2.SGM 02JYP2 asabaliauskas on DSK5VPTVN1PROD with PROPOSALS 38316 Federal Register / Vol. 80, No. 127 / Thursday, July 2, 2015 / Proposed Rules FEDERAL COMMUNICATIONS D Electronic Filers: Comments may be audio format), send an email to fcc504@ COMMISSION filed electronically using the Internet by fcc.gov or call the Consumer & accessing the ECFS: http:// Governmental Affairs Bureau at 202– 47 CFR Parts 2, 15, 80, 90, 97, and 101 fjallfoss.fcc.gov/ecfs2/. 418–0530 (voice), 202–418–0432 (tty). D Paper Filers: Parties that choose to [ET Docket No. 15–99; FCC 15–50] Summary of Notice of Proposed file by paper must file an original and Rulemaking WRC–12 Radiocommunication one copy of each filing. If more than one Conference (Geneva 2012) docket or rulemaking number appears in 1. In this Notice of Proposed the caption of this proceeding, filers Rulemaking (WRC–12 NPRM), the AGENCY: Federal Communications must submit two additional copies for Commission proposes to amend parts 2, Commission. each additional docket or rulemaking 15, 80, 90, 97, and 101 of its rules to ACTION: Proposed rule. number. implement allocation decisions from the D Filings can be sent by hand or Final Acts of the World SUMMARY: In this document, the messenger delivery, by commercial Radiocommunication Conference Commission proposes to implement overnight courier, or by first-class or (Geneva, 2012) (WRC–12 Final Acts) and certain allocation changes from the overnight U.S.
    [Show full text]
  • Enhancement of Laser to X-Ray Conversion by a Double-Foil Gold Target E-Mail: [email protected] and [email protected]
    IOP View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences Plasma Physics and Controlled Fusion Plasma Physics and Controlled Fusion Plasma Phys. Control. Fusion Plasma Phys. Control. Fusion 57 (2015) 075011 (7pp) doi:10.1088/0741-3335/57/7/075011 57 Enhancement of laser to x-ray conversion 2015 by a double-foil gold target © 2015 IOP Publishing Ltd Z Y Ge1, R Ramis2, X H Yang1, T P Yu1, B B Xu1, Y Zhao1, H B Zhuo1, Y Y Ma1, W Yu3 and X J Peng4 PPCF 1 College of Science, National University of Defense Technology, Changsha 410073, People’s Republic of China 075011 2 E.T.S.I. Aeronáuticos, Universidad Politécnica de Madrid, Madrid 28040, Spain 3 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, Z Y Ge et al People’s Republic of China 4 Institute of Applied Physics and Computational Mathematics, Beijing 100088, People’s Republic of China Enhancement of laser to x-ray conversion by a double-foil gold target E-mail: [email protected] and [email protected] Printed in the UK Received 30 January 2015, revised 10 May 2015 Accepted for publication 19 May 2015 Published 18 June 2015 PPCF Abstract A novel double-foil configuration is proposed to improve the laser to x-ray conversion 10.1088/0741-3335/57/7/075011 efficiency from laser irradiating a solid target. One-dimensional radiation hydrodynamic simulations show that the total x-ray conversion efficiency for the double-foil target is as high as 54.7%, which has a 10% improvement compared with the normal target.
    [Show full text]
  • Calibrated Landsat ETM+ Nonthermal-Band Image Mosaics of Afghanistan
    In cooperation with U.S. Agency for International Development Calibrated Landsat ETM+ Nonthermal-Band Image Mosaics of Afghanistan By Philip A. Davis Open-File Report 2006-1345 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior DIRK KEMPTHORNE, Secretary U.S. Geological Survey Mark D. Myers, Director U.S. Geological Survey, Reston, Virginia 20192 2006 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1-888-ASK-USGS For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1-888-ASK-USGS Suggested citation: Davis, P. A., 2006, Calibrated Landsat ETM+ nonthermal-band image mosaics of Afghanistan, U.S. Geological Survey Open-File Report 2006-1345, 18 p. [http://pubs.usgs.gov/of2006/1345/ ]. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. 2 Contents Introduction .........................................................................................................................................................................4 Characteristics of Landsat ETM+ Satellite Image Data ..............................................................................................4
    [Show full text]
  • Introducing the Goes-M Imager
    INTRODUCING THE GOES-M IMAGER Timothy J. Schmit and Elaine M. Prins NOAAlNESDIS Office of Research and Applications Advanced Satellite Products Team Madison, Wisconsin Anthony J. Schreiner Cooperative Institute for Meteorological Studies Madison, Wisconsin ' James J. Gurka NOAAlNESDIS Office of System Development Camp Springs, Maryland Abstract al. 1998; Prins et al. 1998). The current Imager obtains information from four infrared bands (Table 1) and one The latest operational satellite in the GOES series, visible band (Menzel and Purdom 1994). The next satel­ GOES-M, was launched on 23 July 2001. It achieved geo­ lite in the operational GOES series is GOES-12, which stationary orbit on 12 August 2001, and hence is referred was launched 23 July 2001. The GOES-I2/N/OIP Imagers to as GOES-12. The Imager on GOES-12 has been modi­ have been modified to add a band centered at 13.3 f.Lm fied from the previous four imagers in this series. One and improve north-south spatial resolution of a spectral­ change is the addition of a spectral band centered at 13.3 ly modified 6.5 f.Lm band. The addition of the 13.3 f.Lm pm. The GOES-12 Imager also includes a spectrally mod­ band comes at the expense of eliminating the 12 f.Lm band ified 6.5 pm band with an improved spatial resolution on the Imagers. Originally the loss of this band was from 8 km to 4 km at the sub-satellite point. The addition scheduled for only one satellite. However, budgetary con­ of the 13.3 pm band comes at the expense of eliminating straints did not allow for a six-channel imager.
    [Show full text]
  • 1.1-Μm Band Extended Wide-Bandwidth Wavelength-Swept Laser Based on Polygonal Scanning Wavelength Filter
    sensors Communication 1.1-µm Band Extended Wide-Bandwidth Wavelength-Swept Laser Based on Polygonal Scanning Wavelength Filter Gi Hyen Lee 1,†, Soyeon Ahn 1,†, Jinhwa Gene 2 and Min Yong Jeon 1,2,* 1 Department of Physics, College of Natural Sciences, Chungnam National University, 99 Daehak-ro Yuseong-gu, Daejeon 34134, Korea; [email protected] (G.H.L.); [email protected] (S.A.) 2 Institute of Quantum Systems (IQS), Chungnam National University, 99 Daehak-ro Yuseong-gu, Daejeon 34134, Korea; [email protected] * Correspondence: [email protected] † These authors contributed equally to this work. Abstract: We demonstrated a 1.1-µm band extended wideband wavelength-swept laser (WSL) that combined two semiconductor optical amplifiers (SOAs) based on a polygonal scanning wavelength filter. The center wavelengths of the two SOAs were 1020 nm and 1140 nm, respectively. Two SOAs were connected in parallel in the form of a Mach-Zehnder interferometer. At a scanning speed of 1.8 kHz, the 10-dB bandwidth of the spectral output and the average power were approximately 228 nm and 16.88 mW, respectively. Owing to the nonlinear effect of the SOA, a decrease was observed in the bandwidth according to the scanning speed. Moreover, the intensity of the WSL decreased because the oscillation time was smaller than the buildup time. In addition, a cholesteric liquid crystal (CLC) cell was fabricated as an application of WSL, and the dynamic change of the first-order reflection of the CLC cell in the 1-µm band was observed using the WSL. The pitch Citation: Lee, G.-H.; Ahn, S.; Gene, J.; jumps of the reflection band occurred according to the electric field applied to the CLC cell, and Jeon, M.-Y.
    [Show full text]
  • Mid-Infrared Astronomy with the E-ELT: Performance of METIS
    Mid-infrared astronomy with the E-ELT: Performance of METIS S. Kendrewa, L. Jolissainta, B. Brandla, R. Lenzenb, E. Pantinc, A. Glassed, J. Blommaerte, L. Venemaf, R. Siebenmorgeng, F. Molsterh aLeiden Observatory, University of Leiden, PO Box 9513, 2300 RA Leiden, Netherlands; b Max Planck Institute for Astronomy, K¨onigstuhl 17, 69117 Heidelberg, Germany; cCEA Saclay, Gif-sur-Yvette, 91191 cedex, France; dUK Astronomy Technology Centre, Royal Observatory of Edinburgh, Blackford Hill, Edingburgh EH9 3HJ, United Kingdom; eKatholieke Universiteit Leuven, Institute of Astronomy, Celestijnenlaan 200D Bus 2401, 3001 Leuven, Belgium; fAstron, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, Netherlands; gESO, Karl SchwarzschildStrasse 2, 85748 Garching, Germany. hNOVA,PO Box 9513, 2300 RA Leiden, Netherlands. ABSTRACT We present results of performance modelling for METIS, the Mid-infrared European Extremely Large Telescope Imager and Spectrograph. Designed by a consortium of NOVA (Netherlands), UK Astronomy Technology Centre (UK), MPIA Heidelberg (Germany), CEA Saclay (France) and KU Leuven (Belgium), METIS will cover the atmospheric windows in L, M and N-band and will offer imaging, medium-resolution slit spectroscopy (R 1000- 3000) and high-resolution integral field spectroscopy (R 100,000). Our model uses a detailed set of∼ input parameters for site characteristics and atmospheric profiles,∼ optical design, thermal background and the most up-to-date IR detector specifications. We show that METIS will bring an orders-of-magnitude level improvement in sensitivity and resolution over current ground-based IR facilities, bringing mid-IR sensitivities to the micro- Jansky regime. As the only proposed E-ELT instrument to cover this entire spectral region, and the only mid-IR high-resolution integral field unit planned on the ground or in space, METIS will open up a huge discovery space in IR astronomy in the next decade.
    [Show full text]
  • GREAT: the SOFIA High-Frequency Heterodyne Instrument
    A&A 542, L1 (2012) Astronomy DOI: 10.1051/0004-6361/201218811 & c ESO 2012 Astrophysics GREAT: early science results Special feature Letter to the Editor GREAT: the SOFIA high-frequency heterodyne instrument S. Heyminck1,U.U.Graf2,R.Güsten1, J. Stutzki2,H.W.Hübers3,4, and P. Hartogh5 1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: [email protected] 2 I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany 3 Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany 4 Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany 5 Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Straße 2, 37191 Katlenburg-Lindau, Germany Received 12 January 2012 / Accepted 1 March 2012 ABSTRACT We describe the design and construction of GREAT (German REceiver for Astronomy at Terahertz frequencies) operated on the Stratospheric Observatory For Infrared Astronomy (SOFIA). GREAT is a modular dual-color heterodyne instrument for high- resolution far-infrared (FIR) spectroscopy. Selected for SOFIA’s Early Science demonstration, the instrument has successfully per- formed three Short and more than a dozen Basic Science flights since first light was recorded on its April 1, 2011 commissioning flight. We report on the in-flight performance and operation of the receiver that – in various flight configurations, with three different detector channels – observed in several science-defined frequency windows between 1.25 and 2.5 THz. The receiver optics was ver- ified to be diffraction-limited as designed, with nominal efficiencies; receiver sensitivities are state-of-the-art, with excellent system stability.
    [Show full text]
  • L-Band 3G Ground-Air Communication System Interference Study Produced For: Eurocontrol Against Works Order No: 3121 Report No: 72/06/R/319/R December 2006 – Issue 1
    L-Band 3G Ground-Air Communication System Interference Study Produced for: Eurocontrol Against Works Order No: 3121 Report No: 72/06/R/319/R December 2006 – Issue 1 Roke Manor Research Ltd Roke Manor, Romsey Hampshire, SO51 0ZN, UK T: +44 (0)1794 833000 F: +44 (0)1794 833433 [email protected] www.roke.co.uk Approved to BS EN ISO 9001 (incl. TickIT), Reg. No Q05609 The information contained herein is the property of Roke Manor Research Limited and is supplied without liability for errors or omissions. No part may be reproduced, disclosed or used except as authorised by contract or other written permission. The copyright and the foregoing restriction on reproduction, disclosure and use extend to all media in which the information may be embodied. Copy No. ……… This page intentionally left blank L-Band 3G Ground-Air Communication System Interference Study Report No: 72/06/R/319/R Authors: December 2006 – Issue 1 Z. Dobrosavljevic Produced for: Eurocontrol A. Arumugam Against Works Order No: 3121 Approved By KW Richardson ………………………………………………. Project Manager Roke Manor Research Limited The information contained herein is the property of Roke Manor Research Roke Manor, Romsey, Hampshire, SO51 0ZN, UK Limited and is supplied without liability for errors or omissions. No part may be reproduced, disclosed or used except as authorised by contract or other Tel: +44 (0)1794 833000 Fax: +44 (0)1794 833433 written permission. The copyright and the foregoing restriction on Web: http://www.roke.co.uk Email: [email protected] reproduction, disclosure and use extend to all media in which the information Approved to BS EN ISO 9001 (incl.
    [Show full text]